Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1999-07-09
2003-11-11
Maung, Nay (Department: 2684)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S342000, C370S322000, C370S348000, C370S443000
Reexamination Certificate
active
06647002
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a code division multiple access communicating system, a base station for a code division multiple access communicating system and a terminal apparatus for a code division multiple access communicating system, and a code division multiple access communicating method, suitable for a communication of spread spectrum information with a base station over a commonly used channel.
(2) Description of Related Art
With an increase of demand for portable telephones, efficient use of a frequency becomes a serious problem in a mobile communication system. In such circumstances, a code division multiple access (CDMA) communicating system using a spread spectrum technique draws attention as a system having a high frequency efficiency, searches on it being vital for the purpose of practical application thereof.
In a CDMA communicating system, the user uses a mobile station (hereinafter referred to as MS) to transmit a frame to a base station (hereinafter referred to as BS) at a transmittable timing according to notice information transmitted from the BS when making a telephone call, for example.
A frame transmitted from a portable telephone to a BS is transmitted at a timing in a predetermined cycle, as shown by a plurality of arrows in FIG.
24
(
b
). In FIG.
24
(
b
), there are, for example, four timings that the portable telephone can access to the BS in one cycle. Each portable telephone randomly selects any one of the timings to transmit a frame to the BS.
FIG.
24
(
b
) shows that MSs
1
a
through
4
a
transmit frames to the BS at different timings. Incidentally, frames transmitted from the MSs
1
a
through
4
a
are spread using a spreading code and transmitted to the BS. The MSs
1
a
through
4
a
transmit frames at different timings, so that a timing of a phase of the spreading code shifts with a transmit timing even if the spreading code used by MSs
1
a
through
4
a
has the same system. The BS can thereby de-spread each of the frames transmitted from the MSs
1
a
through
4
a
on the basis of the spreading code having a phase different from one another so as to extract the frame.
When the BS receives frames transmitted from the MSs
1
a
through
4
a
, the BS transmits ACKs (Acknowledge) as acknowledge information to the MSs
1
a
through
4
a
(transmitting side), as shown in FIG.
24
(
a
). In ACKs, plural pieces of acknowledge information for the MS
1
a
through
4
a
are collected in a transmission frame, and transmitted.
Each of the MSs
1
a
through
4
a
receives a frame outputted from the BS after transmitting the frame to confirm whether or not the frame having been transmitted to the BS is received by the BS. When there is acknowledge information to the frame having been transmitted from itself in the received frame, each of the MSs
1
a
through
4
a
confirms reception of the frame having been transmitted to the BS by the BS. When each of the MSs
1
a
through
4
a
does not receive acknowledge information to the frame having been transmitted from itself within a predetermined period after transmitting the frame to the BS, the MS performs a re-transmitting process. When receiving ACK to the information having been transmitted from itself within a predetermined period after transmitting the frame to the BS, each of the MSs
1
a
through
4
a
transmits a remaining frame when having the remaining frame to be continuously transmitted to the BS.
When transmitting a plurality of frames to the BS, each of the MSs
1
a
through
4
a
recevies ACK each time the MS transmits a frame, then transmits a remaining frame.
In the case where each of the MSs
1
a
through
4
a
transmits one frame, receives ACK shown in FIG.
24
(
a
), and the MS
1
a
and MS
2
a
transmit remaining packets as shown in FIG.
24
(
b
), each of the MS
1
a
and the MS
2
a
possibly access to the BS at the same timing since each of the MS
1
a
and the MS
2
a
can randomly select an access timing among four access timings in one frame.
At this time, information transmitted from the MS
1
a
and the MS
2
a
is spread using the spreading code having the same phase, so that the BS cannot separate the information transmitted from the MS
1
a
and the MS
2
a
, hence the information is lost. The MS
1
a
and the MS
2
a
therefore cannot receive acknowledge information to the frames that the MS
1
a
and the MS
2
a
have secondary transmitted to the BS, thus the MSs
1
a
and
2
a
have to perform the re-transmitting process. This leads to a decrease of a throughput of the communicating system.
SUMMARY OF THE INVENTION
In the light of the above disadvantage, an object of the present invention is to provide a code division multiple access communicating system, a base station for a code division multiple access communicating system and a terminal apparatus for a code division multiple access communicating system, and a code division multiple access communicating method, in which when a terminal apparatus continuously transmits remaining information after receiving acknowledge information from a base station, the terminal apparatus again accesses to the base station according to an order of a piece of acknowledge information for itself among plural pieces of acknowledge information having been put in a transmission frame, whereby conflict of access timings between terminal apparatus whose acknowledge information has been put in the transmission frame is avoided, thus a decrease of the throughput can be suppressed.
A code division multiple access communicating system according to this invention comprises a base station and a plurality of terminal apparatus exchanging spread spectrum information with the base station over a commonly used channel when communicating with the base station.
The base station comprises a receiving means for receiving an access signal from each of the plural terminal apparatus at the time of random access from each of the plural terminal apparatus, and an acknowledge information transmitting means for collectively putting plural pieces of acknowledge information to reception of the access signals for the plural terminal apparatus in a transmission frame, and transmitting the frame to the plural terminal apparatus when receiving means receives the access signals from the plural terminal apparatus.
Each of the plural terminal apparatus comprises an acknowledge information receiving means for receiving the plural pieces of acknowledge information from the acknowledge information transmitting means of the base station, and a transmitting means for again accessing to the base station according to an order of acknowledge information for its own terminal apparatus among the plural pieces of acknowledge information received from the base station by the acknowledge information receiving means was put after randomly accessing to the base station when there is remaining information to be continuously transmitted to the base station, and transmitting the remaining information.
In the code division multiple access communicating system of this invention, the terminal apparatus again accesses to the base station according to an order of acknowledge information for itself among plural pieces of acknowledge information received from the base station by the acknowledge information receiving means to transmit remaining information, whereby conflict between the terminal apparatus transmitting remaining information is avoided and a decrease of the throughput is suppressed.
A base station for a code division multiple access communicating system of this invention comprises a receiving means for receiving an access signal from each of a plurality of terminal apparatus at the time of random access from each of the plural terminal apparatus, and an acknowledge information transmitting means for collectively putting plural pieces of acknowledge information to reception of the access signals for the plural terminal apparatus in a transmission frame in the order the access signals were received from the plural termin
Kawabata Kazuo
Obuchi Kazuhisa
Suda Kenji
Katten Muchin Zavis & Rosenman
Maung Nay
Sobutka Philip J.
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